U.S. patent application number 15/234627 was filed with the patent office on 2016-12-01 for method and apparatus for transmitting and receiving packet in a communication system.
The applicant listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Sung-Hee HWANG, Kyung-Mo PARK, Hyun-Koo YANG.
Application Number | 20160352460 15/234627 |
Document ID | / |
Family ID | 49854681 |
Filed Date | 2016-12-01 |
United States Patent
Application |
20160352460 |
Kind Code |
A1 |
HWANG; Sung-Hee ; et
al. |
December 1, 2016 |
METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING PACKET IN A
COMMUNICATION SYSTEM
Abstract
A method for transmitting a packet in a communication system is
provided. The method includes dividing a data stream into data
payloads of a predetermined size and adding a common header to each
of the data payloads, to generate a source payload, adding a first
Forward Error Correction (FEC) payload Identifier (ID) to the
source payload and applying an FEC code thereto, to generate an FEC
source packet for a source payload, adding a second FEC payload ID
to at least one parity payload and applying an FEC code thereto, to
generate an FEC parity packet for the at least one parity payload,
and transmitting the FEC source packet and the FEC parity
packet.
Inventors: |
HWANG; Sung-Hee; (Suwon-si,
KR) ; PARK; Kyung-Mo; (Seoul, KR) ; YANG;
Hyun-Koo; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
|
KR |
|
|
Family ID: |
49854681 |
Appl. No.: |
15/234627 |
Filed: |
August 11, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14811068 |
Jul 28, 2015 |
9450702 |
|
|
15234627 |
|
|
|
|
13873739 |
Apr 30, 2013 |
9106376 |
|
|
14811068 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 1/0075 20130101;
H04L 1/0045 20130101; H04L 1/004 20130101; H04L 1/0083 20130101;
H04L 1/0041 20130101; H04L 1/0057 20130101 |
International
Class: |
H04L 1/00 20060101
H04L001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2012 |
KR |
10-2012-0045337 |
Sep 11, 2012 |
KR |
10-2012-0100528 |
Apr 23, 2013 |
KR |
10-2013-0045082 |
Claims
1. A method for receiving a transmission packet in a communication
system, the method comprising: receiving a source packet and a
repair packet as a transmission packet, the source packet being
generated by adding a first payload identifier (ID) to an input
transmission packet, and the repair packet being generated by
adding a second payload ID to a repair symbol, the repair symbol
being generated by encoding a source block; and decoding the
transmission packet, wherein each of the source packet and the
repair packet includes a transmission packet header, wherein the
transmission packet header includes type information indicating if
a forward error correction (FEC) encoding is applied to the
transmission packet, and wherein the second payload ID includes
information indicating a boundary of the source block.
2. The method of claim 1, wherein the first payload ID includes a
sequence number identifying source symbols included in the source
block.
3. An apparatus for receiving a transmission packet in a
communication system, the apparatus comprising: a processor
configured to receive a source packet and a repair packet as a
transmission packet, the source packet being generated by adding a
first payload identifier (ID) to an input transmission packet, and
the repair packet being generated by adding a second payload ID to
a repair symbol, the repair symbol being generated by encoding a
source block; and a decoder configured to decode the transmission
packet, wherein each of the source packet and the repair packet
includes a transmission packet header, wherein the transmission
packet header includes type information indicating if a forward
error correction (FEC) encoding is applied to the transmission
packet, and wherein the second payload ID includes information
indicating a boundary of the source block.
4. The apparatus of claim 3, wherein the first payload ID includes
a sequence number identifying source symbols included in the source
block.
5. An apparatus for transmitting a transmission packet in a
communication system, the apparatus comprising: a processor
configured to: generate a source packet by adding a first payload
identifier (ID) to an input transmission packet, and generate a
parity packet by adding a second payload ID to a repair symbol, the
repair symbol being generated by encoding a source block; and a
transmitter configured to transmit the source packet and the parity
packet as a transmission packet, wherein each of the source packet
and the parity packet includes a transmission packet header,
wherein the transmission packet header includes type information
indicating if a forward error correction (FEC) encoding is applied
to the transmission packet, and wherein the second payload ID
includes information indicating a boundary of the source block.
6. The apparatus of claim 5, wherein the first payload ID includes
a sequence number identifying source symbols included in the source
block.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation application of a prior
application Ser. No. 14/811,068, filed Jul. 28, 2015, which was a
continuation of application Ser. No. 13/873,739, filed on Apr. 30,
2013, which issued as U.S. Pat. No. 9,106,376 on Aug. 11, 2015 and
claimed the benefit under 35 U.S.C. .sctn.119(a) of a Korean patent
application filed on Apr. 30, 2012 in the Korean Intellectual
Property Office and assigned Serial number 10-2012-0045337, of a
Korean patent application filed on Sep. 11, 2012 in the Korean
Intellectual Property Office and assigned Serial number
10-2012-0100528, and of a Korean patent application filed on Apr.
23, 2013 in the Korean Intellectual Property Office and assigned
Serial number 10-2013-0045082, the entire disclosure of each of
which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a communication system.
More particularly, the present invention relates to a method and
apparatus for transmitting and receiving packets in a communication
system.
[0004] 2. Description of the Related Art
[0005] Due to diversification of content and an increase in
high-capacity content, such as High Definition (HD) content and
Ultra High Definition (UHD) content, communication systems may
suffer from increasing data congestion. Because of this, the
content sent by a sender, for example, a host A, may not be
normally delivered to a receiver, for example, a host B, and some
of the content may be lost in its route.
[0006] Generally, since data is transmitted in packets, the loss of
content occurs on a packet basis. The packet is comprised of one
block, for example, a payload of data to be transmitted, address
information, for example, a source address and a destination
address, and management information, for example, a header.
Therefore, if a packet loss occurs in the network, a receiver may
not know the data and management information in the lost packet
since it cannot receive the lost packet, thereby causing the user
inconvenience in various forms such as quality degradation of
audio, quality degradation and image breakage of video, subtitle
missing, file loss, and the like.
[0007] For these reasons, Application Layer-Forward Error
Correction (AL-FEC) is used as a way to recover the data loss which
has occurred in the network, and there is a need for a way to
configure an FEC packet for AL-FEC and transmit and receive the FEC
packet.
[0008] The above information is presented as background information
only to assist with an understanding of the present disclosure. No
determination has been made, and no assertion is made, as to
whether any of the above might be applicable as prior art with
regard to the present invention.
SUMMARY OF THE INVENTION
[0009] Aspects of the present invention are to address at least the
above-mentioned problems and/or disadvantages and to provide at
least the advantages described below. Accordingly, an aspect of the
present invention is to provide a method and apparatus for
configuring a Forward Error Correction (FEC) packet for Application
Layer-Forward Error Correction (AL-FEC) operation and transmitting
and receiving the FEC packet, to improve the reliability of the
network by transmitting a parity packet that is generated using one
or more error-correcting codes together with a data packet in a
communication system supporting a packet-based communication
scheme.
[0010] In accordance with an aspect of the present invention, a
method for transmitting a packet in a communication system is
provided. The method includes generating a source payload by
dividing a data stream into data payloads of a predetermined size
and adding a common header to each of the data payloads, generating
an FEC source packet for the source payload by adding a first FEC
payload Identifier (ID) to the source payload and applying an FEC
code to the source payload, generating an FEC parity packet for at
least one parity payload by adding a second FEC payload ID to the
at least one parity payload and applying an FEC code to the at
least one parity payload, and transmitting the FEC source packet
and the FEC parity packet.
[0011] In accordance with another aspect of the present invention,
an apparatus for transmitting a packet in a communication system is
provided. The apparatus includes a source payload generator
generating a source payload by dividing a data stream into data
payloads of a predetermined size and adding a common header to each
of the data payloads, a controller generating a FEC source packet
by adding a first FEC payload ID to the source payload and applying
an FEC code to the source payload, and generating an FEC parity
packet for at least one parity payload by adding a second FEC
payload ID to at least one parity payload and applying an FEC code
to the at least one parity payload, and a transmitter for
transmitting the FEC source packet and the FEC parity packet.
[0012] In accordance with further another aspect of the present
invention, method for receiving a packet in a communication system
is provided. The method includes determining whether a packet
received from a sender is a Forward Error Correction (FEC) source
packet and an FEC parity packet, and acquiring a source payload
from the FEC source packet, and acquiring a parity payload from the
FEC parity packet, wherein the source payload may be generated by
dividing a data stream into data payloads of a predetermined size
and adding a common header to each of the data payloads, wherein
the FEC source packet may be generated by adding a first FEC
payload Identifier (ID) to the source payload and applying an FEC
code to the source payload, and wherein the FEC parity packet may
be generated by adding a second FEC payload ID to the parity
payload and applying an FEC code to the parity payload.
[0013] In accordance with yet another aspect of the present
invention, an apparatus for receiving a packet in a communication
system is provided. The apparatus includes a controller determining
whether a packet received from a sender is a Forward Error
Correction (FEC) source packet and an FEC parity packet, acquiring
a source payload from the FEC source packet, and acquiring a parity
payload from the FEC parity packet, wherein the source payload may
be generated by dividing a data stream into data payloads of a
predetermined size and adding a common header to each of the data
payloads, wherein the FEC source packet may be generated by adding
a first FEC payload Identifier (ID) to the source payload and
applying an FEC code to the source payload, and wherein the FEC
parity packet may be generated by adding a second FEC payload ID to
the parity payload and applying an FEC code to the parity
payload.
[0014] Other aspects, advantages, and salient features of the
invention will become apparent to those skilled in the art from the
following detailed description, which, taken in conjunction with
the annexed drawings, discloses exemplary embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above and other aspects, features and advantages of
certain exemplary embodiments of the present invention will be more
apparent from the following description taken in conjunction with
the accompanying drawings, in which:
[0016] FIGS. 1A and 1B illustrate a network topology and a data
flow according to an exemplary embodiment of the present
invention;
[0017] FIG. 2 illustrates a configuration of an Motion Pictures
Expert Group (MPEG) Media Transport (MMT) system according to an
exemplary embodiment of the present invention;
[0018] FIG. 3 illustrates a structure of an MMT package according
to an exemplary embodiment of the present invention;
[0019] FIG. 4 illustrates a structure of configuration information
included in an MMT package and its sub information according to an
exemplary embodiment of the present invention;
[0020] FIG. 5 illustrates a structure of a Forward Error Correction
(FEC) packet format according to an exemplary embodiment of the
present invention;
[0021] FIG. 6 illustrates a structure of an FEC packet format in
which a source payload is an MMT transport packet, according to an
exemplary embodiment of the present invention;
[0022] FIG. 7 illustrates a structure of an FEC packet format in
which a source payload is an MMT payload format, according to an
exemplary embodiment of the present invention;
[0023] FIG. 8 is a block diagram illustrating a structure of a
transmitting apparatus according to an exemplary embodiment of the
present invention;
[0024] FIG. 9 is a block diagram illustrating a structure of a
receiving apparatus according to an exemplary embodiment of the
present invention;
[0025] FIG. 10 illustrates an operation of configuring an
information block according to an exemplary embodiment of the
present invention;
[0026] FIG. 11 illustrates an operation of configuring an
information block according to another exemplary embodiment of the
present invention;
[0027] FIG. 12 illustrates a process of mapping an information
symbol in an information block when a Reed-Solomon (RS) code is
used according to an exemplary embodiment of the present
invention;
[0028] FIG. 13 illustrates a process of mapping an information
symbol in an information block when a Low Density Parity Check
(LDPC) code is used according to an exemplary embodiment of the
present invention;
[0029] FIG. 14 illustrates a structure of an RS frame according to
an exemplary embodiment of the present invention;
[0030] FIG. 15 illustrates a structure of an LDPC frame according
to an exemplary embodiment of the present invention;
[0031] FIG. 16 illustrates parity block mapping for RS parity
symbols according to an exemplary embodiment of the present
invention;
[0032] FIG. 17 illustrates parity block mapping for LDPC parity
symbols according to an exemplary embodiment of the present
invention; and
[0033] FIG. 18 illustrates a structure of an H matrix according to
an exemplary embodiment of the present invention.
[0034] Throughout the drawings, like reference numerals will be
understood to refer to like parts, components, and structures.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0035] The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
exemplary embodiments of the invention as defined by the claims and
their equivalents. It includes various specific details to assist
in that understanding but these are to be regarded as merely
exemplary. Accordingly, those of ordinary skilled in the art will
recognize that various changes and modifications of the embodiments
described herein can be made without departing from the scope and
spirit of the invention. In addition, descriptions of well-known
functions and constructions may be omitted for clarity and
conciseness.
[0036] The terms and words used in the following description and
claims are not limited to the bibliographical meanings, but, are
merely used by the inventor to enable a clear and consistent
understanding of the invention. Accordingly, it should be apparent
to those skilled in the art that the following description of
exemplary embodiments of the present invention is provided for
illustration purpose only and not for the purpose of limiting the
invention as defined by the appended claims and their
equivalents.
[0037] It is to be understood that the singular forms "a," "an,"
and "the" include plural referents unless the context clearly
dictates otherwise. Thus, for example, reference to "a component
surface" includes reference to one or more of such surfaces.
[0038] First, the terms to be used herein will be defined as
follows: [0039] Forward Error Correction (FEC) Code: an
error-correcting code for correcting an error or an erasure symbol;
[0040] FEC Frame: a codeword, which is generated by FEC-encoding
the data to be protected, and is comprised of an information part
and a parity part or repair part; [0041] Symbol: a unit of data
processed by the FEC code; [0042] Information Symbols: unprotected
data or padding symbols which is the information part of an FEC
frame; [0043] Codeword: an FEC frame generated by FEC-encoding
information symbols; [0044] Parity Symbols: parity symbols of an
FEC frame generated by FEC-encoding an information symbols; [0045]
Packet: a transmission unit comprised of a header and a payload;
[0046] Payload: a piece of user data which is to be transmitted by
the sender and which is placed inside a packet; [0047] Packet
Header: a header for a packet including a payload; [0048] Source
Payload: a payload comprised of source symbols; [0049] Information
Payload: a payload comprised of information symbols; [0050] Parity
Payload: a payload comprised of parity symbols; [0051] Source
Block: a set of payloads each comprised of one or more source
payloads; [0052] Information Block: a set of payloads each
comprised of one or more information payloads; [0053] Parity Block:
a set of payloads each comprised of one or more parity payloads;
[0054] FEC Block: a set of codewords, or a set of payloads each
comprised of an information block and a parity block; [0055] FEC
Delivery Block: a set of payloads each comprised of a source block
and a parity block; [0056] FEC Packet: a packet for carrying an FEC
block; [0057] Source Packet: a packet for carrying a source block;
[0058] Repair Packet: a packet for carrying a repair block; [0059]
FEC Packet Block: a set of packets for carrying an FEC delivery
block; [0060] Motion Pictures Expert Group (MPEG) Media Transport
(MPEG) Media Transport (MMT): an international standard established
to efficiently transmit MPEG data; [0061] Source Flow: a Source
Flow is a sequence of Source Payloads identified by the same Source
Flow identifier to deliver one or more MMT Assets from one MMT
Server to one or more MMT Clients; [0062] Parity Flow: a Parity
Flow is a sequence of Parity Payloads, which are generated by FEC
encoding to protect a Source Flow, identified by the same Parity
Flow identifier; [0063] FEC Flow: an FEC Flow consists of a Source
Flow and its associated one or more Parity Flows; [0064] FEC
Payload Identifier (ID): information that identifies the
Information Payloads or sub-Payloads carried by an FEC Source
Packet or the Parity Payloads carried by an FEC Parity Packet;
[0065] FEC Source Payload ID: FEC Payload ID for Source Packet;
[0066] FEC Parity Payload ID: FEC Payload ID for Parity Packet;
[0067] Access Unit (AU): an access unit is the smallest data entity
to which timing information can be attributed, for non-timed data,
whose timing information is not associated, the AU is not defined;
[0068] Media Fragment Unit (MFU): is a generic container,
independent of any specific media codec, containing coded media
data that is independently consumable by a media decoder, and is
equal to or smaller than an AU and contains information that can be
utilized by delivery layers; [0069] MMT Processing Unit: is a
generic container, independent of any specific media codec,
containing one or more AUs and additional delivery and consumption
related information, wherein for non-timed data, the MPU contains
portion of data without an AU boundaries identified, and it defines
coded media data unit that can be completely and independently
processed in MMT, and in this context processing means
encapsulation into MMT Package or packetization for delivery;
[0070] MMT Asset: is a logical data entity that is composed of one
or more MPUs, and is the largest data unit for which same
composition information and transport characteristics are applied,
and an MMT Asset contains only one kind of data type including
packaged or multiplexed data, e.g. a portion of audio ES, a portion
of video ES, an MPEG-U Widget Package, a portion of MPEG-2 TS, a
portion of MP4 file, and a portion of MMT Package; [0071] MMT
Composition Information (MMT-CI): is description about spatial and
temporal composition of MMT Assets; [0072] MMT Media
Characteristics for Transmission (MMT-MCT): is description about
required Quality of Service (QoS) for delivery of MMT Assets.
MMT-MCT is represented by the parameters agnostic to specific
delivery environment; [0073] MMT Package: is a logically structured
collection of data, which is composed of one or more MMT Assets,
MMT-CI and MMT-MCT, and may also have assigned descriptive
information such as an identifier; [0074] MMT Payload Format
(MMT-PF): is a format of payload for MMT Package or MMT signaling
message to be carried by MMT Protocol or Internet application layer
protocols, e.g. Real Time Protocol (RTP); and [0075] MMT Transport
Packet (MMTP): is an application layer protocol for delivering
MMT-PF over an Internet Protocol (IP) network.
[0076] The terms `parity` and `repair` as used herein have the same
meanings, so they are interchangeable with each other.
[0077] FIGS. 1A and 1B illustrate a network topology and a data
flow according to an exemplary embodiment of the present
invention.
[0078] Referring to FIG. 1A, a network topology includes a host A
102 operating as a sender, and a host B 108 operating as a
receiver. The host A 102 is connected to the host B 108 via one or
more routers 104 and 106. The host A 102 and the host B 108 are
connected to the routers 104 and 106 via Ethernets 118 and 122, and
the routers 104 and 106 may be connected to each other via a fiber,
satellite communication or other possible physical network, such as
Ethernet 120. Data flow between the host A 102 and the host B 108
is achieved by a link layer 116, an Internet layer 114, a transport
layer 112 and an application layer 110.
[0079] Referring to FIG. 1B, the application layer 110 generates
data 130 to be transmitted, by Application Layer-FEC (AL-FEC). The
data 130 may be Real Time Protocol (RTP) packet data generated by
dividing the data that is compressed in an Audio/Video (AV) codec,
using an RTP protocol, or may be MMT packet data generated in
accordance with MMT. The data 130 is converted by the transport
layer 112 into a User Datagram Protocol (UDP) packet 132 into
which, for example, a UDP header is inserted. The Internet layer
114 generates an IP packet 134 by attaching an IP header to the UDP
packet 132. The link layer 116 configures a frame 136 to be
transmitted, by attaching a frame header and, if necessary, a frame
footer to the IP packet 134.
[0080] FIG. 2 illustrates a configuration of an MMT system
according to an exemplary embodiment of the present invention.
[0081] Referring to FIG. 2, a configuration of an MMT system is
illustrated on the left, and the detailed structure of a delivery
function is illustrated on the right. A media coding layer 205
compresses audio and/or video data, and delivers it to an
encapsulation function layer 210, which may also be referred to as
an E. Layer 210. The encapsulation function layer 210 packetizes or
encapsulates the compressed audio/video data in a form similar to a
file format, and delivers it to a delivery function layer 220,
which may also be referred to as a D. Layer.
[0082] The delivery function layer 220 formats an output of the
encapsulation function layer 210 into an MMT payload, adds an MMT
transport packet header thereto, and delivers it to a transport
protocol layer 230 in the form of an MMT transport packet.
Alternatively, the delivery function layer 220 delivers an output
of the encapsulation function layer 210 to the transport protocol
layer 230 in the form of an RTP packet using the existing RTP
protocol. Thereafter, the transport protocol layer 230 converts the
input RTP packet into any one of a UDP packet and a Transmission
Control Protocol (TCP) packet, and transfers it to an IP layer 240.
Finally, the IP layer 240 converts an output of the transport
protocol layer 230 into an IP packet, and transmits it using an IP
protocol.
[0083] An FEC packet according to the present exemplary embodiments
is available in the form of at least one of an MMT payload format,
an MMT transport packet, and an RTP packet. A control function
layer 200, which may also be referred to as a C. Layer 200, manages
a presentation session and a delivery session.
[0084] FIG. 3 illustrates a structure of an MMT package according
to an exemplary embodiment of the present invention.
[0085] Referring to FIG. 3, an MMT package 310 is transmitted and
received to/from a client 350 via delivery function layers 330-1
and 330-2 of the network, and includes MMT assets 303-1 to 303-3,
composition information 301, and transport characteristics 305-1
and 305-2. The MMT package 310 may utilize configuration
information. The configuration information is comprised of a list
of the MMT assets 303-1 to 303-3, the composition information 301,
and the transport characteristics 305-1 and 305-2.
[0086] Description information describes the MMT package 310 and
the MMT assets 303-1 to 303-3. The composition information 301
assists in consumption of the MMT assets 303-1 to 303-3. The
transport characteristics 305-1 and 305-2 provide information for
delivery of the MMT assets 303-1 to 303-3. The MMT package 310
describes transport characteristics of each MMT asset separately.
The transport characteristics 305-1 and 305-2 include error
resiliency information, and simple transport characteristic
information for one MMT asset that may or may not be lost. The
transport characteristics 305-1 and 305-2 may include Quality of
Service (QoS) information and allowable loss and allowable delay
information of each MMT asset.
[0087] FIG. 4 illustrates a structure of configuration information
included in an MMT package and its sub information according to an
exemplary embodiment of the present invention.
[0088] As illustrated in FIG. 4, configuration information 310
includes package identification information 312, asset list
information 314, which is a component of the package, composition
information 316, transport characteristics 318, and additional
information together with content, and provides structural
information indicating how and where these components are included
in the package.
[0089] FIG. 5 illustrates a structure of an FEC packet format
according to an exemplary embodiment of the present invention.
[0090] An FEC source packet 510, which is an FEC packet for a
source payload 520 that includes a common header 522, an optional
header 524, and data 528, is comprised of a common header 512, an
optional header 514, an FEC payload ID 516 for the source payload
520, and data 518. The FEC source packet 510 is generated by adding
the FEC payload ID 516 for the source payload 520 to the source
payload 520 comprised of the common header 512, the optional header
514 and the data 518.
[0091] An FEC parity packet 530, which is an FEC packet for a
parity payload 540, is comprised of a common header 532, an FEC
payload ID 536 for a parity payload, and a parity payload 538. The
FEC parity packet 530 is generated by adding the common header 532
and the FEC payload ID 536 for a parity payload to the parity
payload 538 generated by FEC encoding.
[0092] Although it is assumed in FIG. 5 that the FEC payload ID 516
is placed in front of the data 518 or the parity payload 538, the
present invention is not limited thereto, and the FEC payload ID
516 may be placed at the rear of the data 518 or the parity payload
538 or at any similar and/or suitable location.
[0093] It is preferable that a common header, which may be the
common header 512 or the common header 532 or any other common
header such as common header 522, is placed in the same position
within the FEC packet. The common header, which may be the common
header 512, 522, or 532, includes a Type information field to make
it possible to easily determine whether an FEC packet received at
an FEC packet receiver is an FEC source packet or an FEC parity
packet. In addition, the common header, which may be the common
header 512, 522, or 532, may include an information field
indicating whether FEC is applied. In some cases, the information
field indicating whether FEC is applied is stored in, and carried
by, a separate packet for delivering control information, which is
different from the FEC packet. Data of the FEC source packet may
have several data types, which may include, for example, audio
data, video data, file data, timed data, non-timed data, MPU, MFU
and the like. The several data types may be distinguished by a
value of a Type filed of the common header, which may be the common
header 512, 522, or 532. Particularly, in the case of the FEC
parity packet 530, the parity packet may be distinguished from the
source packet by setting a value of the Type field of the common
header 532 as information indicating parity. However, if there are
multiple parities, they are separately distinguished. For example,
in the case of Two Stages Coding Structure, Parity1 and Parity2 are
additionally distinguished.
[0094] The term `common header information` as used herein refers
to a header having an information field that is applied in common
to a parity payload, in the header information for a data payload.
The common header information includes information that makes it
possible to determine whether a received packet is a packet for a
data payload or a packet for a parity payload. In addition, the
information indicating whether FEC is applied to the received FEC
packet may be carried in the FEC packet, or carried by a separate
packet for control information, which is different from the FEC
packet. The common header information indicating whether the FEC is
applied or not may indicate or mark application of FEC in the
common header when a source payload is generated, i.e., before FEC
encoding, and then undergo FEC encoding. Alternatively, the common
header information indicating whether the FEC is applied or not may
indicate non-application of FEC in the common header when a source
payload is generated, and then indicate application of FEC when an
FEC packet for a source payload is generated by adding an FEC
payload ID for a source payload to the source payload after FEC
encoding. In the latter case, recognizing that a received FEC
packet for a source payload is an FEC-applied packet, a receiver
may change the common header information indicating whether the FEC
is applied or not to indicate again non-application of FEC, then
generates an FEC packet for a source payload, and then performs FEC
decoding thereupon. As the common header is placed in a fixed
position, such as in front of or at the rear of the FEC packet, the
receiver may determine whether a received FEC packet is a packet
for a data payload or a packet for a parity payload.
[0095] Table 1 below illustrates, as an example of a common header
of the present exemplary embodiments, FEC type information in an
MMT packet header which indicates whether FEC is applied, whether
the received packet is an FEC source packet, and whether the
received packet is an FEC repair packet.
TABLE-US-00001 TABLE 1 value of FEC_type Value Description 0 MMT
packet without AL-FEC protection 1 MMT packet with AL-FEC
protection; FEC source packet 2 MMT packet for repair symbol; FEC
repair packet 3 Reserved for future use
[0096] In Table 1, FEC type=0 indicates an MMT packet to which FEC
is not applied. FEC type=1 indicates an MMT packet to which FEC is
applied. FEC type=2 indicates an MMT packet for a parity payload,
which is generated after FEC encoding.
[0097] For the data a sender is to transmit by applying FEC, the
sender generates MMT packets, i.e., a source payload, whose FEC
type is set as `1`, then generates information payloads, and then
performs FEC encoding thereupon to generate a parity payload. For
the parity payload generated by FEC encoding, an FEC packet for a
parity payload is generated by adding an MMT header whose FEC type
is set as `2`, an MMT payload header, and an FEC payload ID for a
parity payload, and then the FEC packet for a parity payload, such
as FEC parity packet 530, is transmitted together with the FEC
packet for a source payload, such as the FEC Source Packet 510.
Based on the FEC type information in the MMT packet header of
received MMT packets, a receiver determines whether FEC is applied
to the received packet and whether the received packet is an FEC
source packet or an FEC repair packet, and then performs FEC
decoding on the FEC-applied FEC source packet and FEC repair
packet, thereby recovering the packet that is lost during
transmission of the packet.
[0098] Alternatively, for the data the sender desires to transmit
by applying FEC, the sender generates MMT packets whose FEC type is
set as `0`, then generates information payloads, and then performs
FEC encoding thereupon to generate a parity payload. When
generating an FEC source packet for a source payload by adding an
FEC payload ID to the MMT packet after performing FEC encoding, the
sender changes the FEC type in the MMT packet header to `1`. In
other words, in the case of an MMT packet to which FEC is applied,
the MMT packet is input to an FEC module after the FEC type is set
as `0`, and in the case of an FEC packet for a source payload after
FEC encoding, the FEC type is set as `1`. For a parity payload
generated by FEC encoding, the sender generates an FEC packet for a
parity payload by adding an MMT header with FEC type=2, an MMT
payload header, and an FEC payload ID for a parity payload, to the
generated parity payload, and then transmits it together with an
FEC packet for a source payload. Based on the FEC type information
in the MMT packet header of received MMT packets, the receiver
determines whether FEC is applied to the received packet and
whether the received packet is an FEC source packet or an FEC
repair packet, then removes the FEC payload ID from the FEC source
packet using the FEC-applied FEC source packet, which has the FEC
type=1, and FEC repair packet, which has the FEC type=1, converts
them into MMT packets for a source payload by changing the FEC type
to FEC type=0, and then performs FEC decoding on the parity payload
of the FEC repair packet, thereby recovering the packet that is
lost during transmission of the packet.
[0099] The optional header 514 of the FEC source packet 510 is
information that is applied only to the source packet, and includes
at least one of fragmentation status information of the MPU and/or
the MFU, header length information, and information indicating the
identity of an asset related to data of the packet. Although this
information may be an asset ID in the present exemplary
embodiments, it is preferable to increase the transmission
efficiency by transmitting compressed asset ID information that is
mapped to the asset ID. In this case, the asset ID and the
compressed asset ID information mapped thereto are transmitted in
an out-of-band manner, such as via an out-of-band signal.
[0100] In the case of an FEC header, an FEC payload ID for a source
packet and an FEC payload ID for a parity packet may be identical
to or different from each other, depending on the information block
generation method, the FEC control information, and the FEC-related
control information arrangement method. FEC payload ID information
includes at least one of FEC flow information, FEC coding structure
information, source packet count information or the number of
source packets, information payload count information, parity
packet count information, a Packet Sequence Number such as a
Source/Parity Packet Sequence Number, or Information/Parity Payload
ID which is information indicating indexes of information payloads
and parity payloads in an FEC block, and Block Boundary Info or
Source Block Number.
[0101] In the MMT system illustrated in FIG. 2, when FEC is applied
thereto, the FEC packet is input with the MMT D.2 Layer or an
application protocol such as RTP, as an output of the MMT D.1
Layer. However, if FEC is not applied thereto, the FEC packet
becomes a source payload and is an output of the MMT D.1 Layer
since it does not require the FEC payload ID. Although not
illustrated in FIG. 2, the FEC packet of the present exemplary
embodiments may include an FEC payload ID if FEC is applied
thereto, and the FEC packet is a source payload itself without the
FEC payload ID if FEC is not applied thereto.
[0102] An MMT server transmits one or multiple MMT assets to an MMT
client. Each asset is comprised of one or multiple MPUs, and each
MPU is packetized into one or multiple MMT Payload Formats
(MMT-PFs) in the D.1 Layer. An MMT Transport Packet (MMT-TP) is
generated by adding a D.2 header and is transferred to a lower
layer. In a case having transmission of multiple MMT assets, a D.2
header of the MMT-TP for each of the assets is transmitted by
storing information, for example, an Asset ID, for identifying each
of the assets, indicating data of which of the assets each of the
transmission MMT-TPs carries. As multiple MMT assets being
transmitted constitute one source flow for an individual MMT asset,
one parity flow is generated and protected by FEC. Alternatively,
as two or more assets constitute one source flow, one parity flow
is generated and protected by FEC. Some assets may be protected by
FEC while other assets may not be protected by FEC. For example, in
the Two Stage FEC coding structure or Layer-Aware FEC coding
structure, two or more parity flows may be generated and protected
in one source flow.
[0103] When protected by FEC, one source flow comprised of one or
multiple MMT assets is transmitted after converting the parity
payloads in the parity flow generated by FEC into MMT-TP, like the
MMT asset, and each D.2 header is transmitted by storing
information, for example, the Asset ID, for identifying the parity
payloads. For example, in the Two Stage FEC or Layer-Aware (LA)-FEC
coding structure, if two or more parity flows are generated, each
parity flow may be distinguished by a parity flow ID. In this case,
FEC flow IDs corresponding to the number of transmission FEC flows
are defined as FEC out-of-band signals, and mapping information for
a source flow and a parity flow corresponding to each FEC flow ID
is provided.
[0104] For example, in a case where a video asset, an audio asset,
a widget asset, and a file asset are transmitted, if the video,
audio and widget assets are composed as one source flow and
protected in the Two Stage FEC coding structure, and if the file
asset is composed as another source flow and protected in the One
Stage FEC coding structure, then an FEC out-of-band signal carries
the following information. [0105] Video Asset: Asset ID=1 [0106]
Audio Asset: Asset ID=2 [0107] Widget Asset: Asset ID=3 [0108] File
Asset: Asset ID=4 [0109] Number of FEC Flows=2 [0110] .box-solid.
FEC Flow ID=1 [0111] FEC coding structure: Two Stage FEC coding
structure [0112] Source Flow: Asset ID 1, 2, 3 [0113] Parity Flow1:
Asset ID 101 [0114] Parity Flow2: Asset ID 102 [0115] .box-solid.
FEC Flow ID=2 [0116] FEC coding structure: One Stage FEC coding
structure [0117] Source Flow: Asset ID 4 [0118] Parity Flow: Asset
ID 103 [0119] In addition, by setting; [0120] Asset ID=1 in an MMT
TP Header carrying Video Asset, [0121] Asset ID=2 in MMT TP Header
carrying Audio Asset, [0122] Asset ID=3 in MMT TP Header carrying
Widget Asset, [0123] Asset ID=101 in MMT TP Header carrying Parity
Flow1, [0124] Asset ID=102 in MMT TP Header carrying Parity Flow2,
[0125] Asset ID=4 in MMT TP Header carrying File Asset, and [0126]
Asset ID=103 in MMT TP Header carrying Parity Flow for File
Asset,
[0127] The receiver may smoothly perform FEC decoding by
determining, based on the FEC out-of-band signal and the Asset ID
information in the MMT TP header, that the Asset ID fields with
values of 1, 2, 3, 101 and 102 constitute one FEC flow and that the
Asset ID fields with values of 4 and 103 constitute another FEC
flow.
[0128] FIG. 6 illustrates a structure of an FEC packet format in
which a source payload is an MMT transport packet, according to an
exemplary embodiment of the present invention.
[0129] Referring to FIG. 6, an FEC source packet 610, of a source
payload 620, is comprised of a D2 header 613 which consists of a
common header 612 and an optional header 614, a D1 payload format
616, and an FEC payload ID 618. An FEC parity packet 630 is
comprised of a common header 632, an FEC payload ID 636, and a
parity payload 638. In the common header 632, an ID field for
distinguishing the assets is configured, and in the case of a
parity packet, an ID value for identifying the parity flow is set.
The common header 632 may include a Global Sequence Number field, a
Delivery Time Stamp field, and the like. Although not illustrated,
in the case of FIG. 6, for the FEC parity packet 630, the common
header 632 may be followed by an optional header. In other words,
the D2 header 613 of the FEC source packet may be the same as a D2
header of the FEC parity packet (not shown), which includes the
common header 632 and the optional header. In this regard, since
the MMT TP header performs a function of a protocol, the network
entity may drop the FEC parity packet when it drops a packet
depending on the congestion situation of the network. Therefore,
the FEC parity packet may have the same header structure as that of
the FEC source packet.
[0130] FIG. 7 illustrates a structure of an FEC packet format in
which a source payload is an MMT payload format, according to an
exemplary embodiment of the present invention.
[0131] An FEC source packet 710, of a source payload 720, is
comprised of an MMT TP header 712, a D1 header 713 which is
consists of a common header 714 and an optional header 716, a D1
payload 718, and an FEC payload ID 720, and an FEC parity packet
730 is comprised of an MMT TP header 732, a common header 736, an
FEC payload ID 738, and a parity payload 740. In this case, an
Asset ID field of the MMT TP header 732 is prepared. For an Asset
ID field for the FEC source packet 710, an ID value for identifying
each of the assets is set. For an Asset ID field for the FEC parity
packet 730, an ID value for identifying a parity flow is set. The
common header 714 and 736 stores the same information as that in
FIG. 5.
[0132] FIG. 8 is a block diagram illustrating a structure of a
transmitting apparatus according to an exemplary embodiment of the
present invention.
[0133] Referring to FIG. 8, an FEC control information generator
601 determines whether FEC is applied or not, and generates
FEC-related control information if FEC is applied. A source payload
generator 603 receives a data stream for transmission of an MMT
asset from an upper encapsulation layer, divides it into data
payloads of a predetermined size, and adds a common header and an
optional header thereto, to generate a source payload. Based on the
FEC control information from the FEC control information generator
601, the source payload generator 603 transfers, to an information
block generator 605, a source block comprised of a predetermined
number of source payloads from a sequence of source payloads having
the same FEC flow.
[0134] Based on the FEC control information, the information block
generator 605 generates an information block from the source block
received from the source payload generator 603, and outputs the
information block to an FEC encoder 607. Based on the input
information block and the FEC control information, the FEC encoder
607 generates predetermined parity data and inputs it to the source
payload generator 603. Based on the FEC control information, the
source payload generator 603 generates a parity payload with the
input parity data.
[0135] An FEC packet generator 609 generates an FEC parity packet
by adding a common header and an FEC header to the parity payload,
generates an FEC source packet by adding an FEC header to the
generated source payload, and outputs the final FEC packets to a
transmitter 611. The transmitter 611 transmits the FEC packets to
the lower layer. If FEC is not applied, then the source payload
generator 603 and the FEC packet generator 609 generate a source
payload based on the data stream and FEC control information, and
then transfer it to the transmitter 611 as an FEC packet. In the
case of the MMT system illustrated in FIG. 2, the FEC packet is
transferred with the MMT D.2 Layer or an application protocol like
RTP.
[0136] Although not illustrated in the drawing, a controller
divides a data stream into data payloads of a predetermined size
and adds a header to each of the data payloads to generate a source
payload. The controller adds a first FEC payload ID to the source
payload and applies FEC encoding thereto to generate an FEC source
packet for a source payload. The controller adds a second FEC
payload ID to at least one parity payload and applies FEC encoding
thereto to generate an FEC parity packet for the at least one
parity payload. The transmitter 611 transmits the FEC source packet
and the FEC parity packet.
[0137] FIG. 9 is a block diagram illustrating a structure of a
receiving apparatus according to an exemplary embodiment of the
present invention.
[0138] Referring to FIG. 9, an FEC packet receiver 701 receives a
packet stream, then determines, based on a common header of a
packet, whether FEC is applied to the packet and whether the packet
is a source packet or a parity packet, then acquires FEC-related
control information from an FEC header of the source packet and an
FEC header of the parity packet if FEC is applied to the packet,
and then transfers the FEC-related control information to an FEC
controller 709. If there are multiple FEC flows, the FEC controller
709 distinguishes flow-specific control information and performs
FEC decoding for each flow.
[0139] A source payload reconstructor 703 transfers, to a data
stream unit, data of the packet, i.e., a source payload, to which
FEC is not applied, from among the received FEC packets. If FEC is
applied, then the source payload reconstructor 703 distinguishes
source payloads which are not received as source payloads received
in packets having the same FEC flow. If the source payload
reconstructor 703 has received all of the source payloads based on
the FEC control information, then it outputs data corresponding
thereto.
[0140] Otherwise, the source payload reconstructor 703 outputs the
received parity payloads from the FEC parity packet to an FEC block
reconstructor 705 together with the received source payloads. The
FEC block reconstructor 705 reconstructs an FEC block comprised of
an information block and a parity block from the received source
payloads and parity payloads based on the FEC control information
by erasing the lost payloads, and outputs the reconstructed FEC
block to an FEC decoder 707.
[0141] Based on the FEC control information received from the FEC
controller 709, the FEC decoder 707 recovers the lost information
payloads by performing FEC decoding, and outputs the recovered
information payloads to the FEC block reconstructor 705. Based on
the FEC control information, the FEC block reconstructor 705
recovers a source payload from the recovered information payloads
if necessary, using, for example, the information payload
reconstructed from the received source payloads, and outputs the
recovered source payload to the source payload reconstructor 703.
The source payload reconstructor 703 transfers data of the
recovered source payload and received source payloads to the upper
layer.
[0142] In the exemplary embodiment of FIG. 9, the FEC controller
709 distinguishes an in-band signal from an out-band signal in
generating FEC-related control information. The FEC controller 709
transmits the in-band signal in an FEC packet as an FEC header. In
the case of the MMT system illustrated in FIG. 2, the FEC
controller 709 transmits the out-band signal to a receiver by means
of the C. Layer or a Session Description Protocol (SDP).
[0143] A controller, which may be any suitable type of hardware
such as an Integrated Circuit (IC) and which is not shown,
determines whether a packet received from a sender is an FEC source
packet and an FEC parity packet, and acquires a source payload from
the FEC source packet and a parity payload from the FEC parity
packet. The source payload is generated by dividing a data stream
into data payloads of a predetermined size, and adding a header to
each of the data payloads. The FEC source packet is generated by
adding a first FEC payload ID to the source payload and applying an
FEC code thereto. The FEC parity packet is generated by adding a
second FEC payload ID to the parity payload and applying an FEC
code thereto.
[0144] FIG. 10 illustrates an example of configuring an information
block in an FEC block generator according to an exemplary
embodiment of the present invention.
[0145] Referring to FIG. 10, upon receiving 8 source payloads SPL
#0 to SPL #7, each having a variable packet size, the FEC block
generator adds padding data so as to match the size of each payload
to that of the payload having the maxim length, for example, S_max,
and then generates an information block comprised of 8 information
payloads IPL#0 to IPL#7. Although it is assumed in the exemplary
embodiment FIG. 10 that the length of the information payload is
set to match with the maximum size S_max of the source payload, the
present invention is not limited thereto, and the length of the
information payload may be set to be less than S_max depending on
the system complexity and memory requirements.
[0146] FIG. 11 illustrates an operation of configuring an
information block according to another exemplary embodiment of the
present invention.
[0147] Referring to FIG. 11, upon receiving 6 source payloads SPL
#0 to SPL #5, each having a variable packet size, the FEC packet
generator arranges payloads having different sizes in a row and
divides them in the maximum length, for example, S_max, of an
information payload, to generate an information block comprised of
5 information payloads IPL#0 to IPL#4. The last information
payload, IPL#4, may include padding data. In the exemplary
embodiment of FIG. 11, since a boundary of a source block does not
match with a boundary of an information payload, the information
required to extract a source payload from an information block,
such as the length of each payload, should be included in the
information block, or should be delivered to a receiver in a
separate way. Although it is assumed in the exemplary embodiment of
FIG. 11 that the maximum length S_max of a source payload and the
length of an information payload are set to be the same, a length
of an information payload may be set to be less than S_max
depending on the system complexity and memory requirements.
[0148] Referring to FIG. 8, the FEC encoder 607 calculates parity
symbols from the input information block using a predetermined FEC
encoding algorithm, then generates a parity payload comprised of
the parity symbols, and then outputs the parity payload in the form
of a parity block.
[0149] FIG. 12 illustrates a process of mapping an information
symbol in an information block when a Reed-Solomon (RS) code is
used according to an exemplary embodiment of the present
invention.
[0150] FIG. 13 illustrates a process of mapping an information
symbol in an information block when a Low Density Parity Check
(LDPC) code is used according to an exemplary embodiment of the
present invention.
[0151] Referring to FIGS. 12 and 13, if K, which is a number of
information bits, is less than or equal to 200, from an information
block, then the FEC encoder maps a source block to the information
block to generate an information symbol for RS coding as
illustrated in FIG. 12, or the FEC encoder may generate an
information symbol for LDPC coding as illustrated in FIG. 13.
[0152] FIG. 14 illustrates a structure of a RS frame according to
an exemplary embodiment of the present invention.
[0153] FIG. 15 illustrates a structure of an LDPC frame according
to an exemplary embodiment of the present invention.
[0154] Referring to FIGS. 14 and 15, a parity symbol is generated
by performing RS and LDPC encoding on each information symbol, as
illustrated in FIGS. 14 and 15. In the case of FIG. 15, although
shortening and puncturing are not illustrated, a parity symbol may
be generated by performing shortening and puncturing for a variety
of K information bits and P parity bits using an LDPC code having a
predetermined length. It will be apparent to those of ordinary
skill in the art that only one of shortening and puncturing may be
performed selectively.
[0155] FIG. 16 illustrates parity block mapping for RS parity
symbols according to an exemplary embodiment of the present
invention.
[0156] FIG. 17 illustrates parity block mapping for LDPC parity
symbols according to an exemplary embodiment of the present
invention.
[0157] Referring to FIGS. 16 and 17, an RS parity block and an LDPC
parity block are generated from the generated parity symbols, as
illustrated in FIGS. 16 and 17. Next, RS and LDPC code
specifications are illustrated. A primitive polynomial of an RS(N,
K) code over the finite field GF(2 8) is defined as p(x)=x 8+x 4+x
3+x 2+1. A symbol in GF(2 8) may be represented as (a 7, a 6, a 5,
a 4, a 3, a 2, a, 1), where a=00000010 in binary.
[0158] Each RS codeword rsc is an RS(240, 40) code over the finite
field GF(2 8), which is expressed as rsc=(e0, e1, . . . , e199,
p200, . . . , p239) when expressed as a vector. For the RS(240, 40)
code, information is 200 bytes and parity is 40 bytes. An LDPC
(K+P, K) code over the finite field GF(2) has a Quasi Cyclic
(QC)-LDPC structure comprised of K information bits and P parity
bits, where K=L.times.400, P=L.times.80, and L=1, 2, 4, 8 or 16. In
particular, a parity part of LDPC has an approximate shape of a
triangular matrix, as illustrated in FIG. 18.
[0159] FIG. 18 illustrates a structure of an H matrix according to
an exemplary embodiment of the present invention, in which K=400,
and P=L.times.80 (L=1, 2, 4, 8 or 16).
[0160] Referring to FIG. 18, although an RS code and an LDPC code
have been considered so far by way of example only, any other codes
may be applied, such as FEC codes such as Raptor, RaptorQ, XOR
codes, or any other similar and/or suitable codes. An FEC packet
generation method according to an exemplary embodiment of the
present invention will be described as follows.
[0161] The payload type of a common header of each packet is set to
correspond to the payload during its transmission. In other words,
the payload type of a packet for a source payload indicates a
source payload, and the payload type of a packet for a repair
payload indicates a repair payload. A sequence number for source
packets is sequentially granted. Similarly, a sequence number for
repair packets is sequentially granted, but for the repair packets,
a starting sequence number is set to start at a starting sequence
number of, for example, a source packet so that the boundary of a
repair block in the FEC block may be determined. In other words, by
setting the sequence numbers for source packets and repair packets
in an FEC block to have a correlation, the boundary of repair
blocks or the boundary of a repair block, may be determined. A
starting sequence number of the FEC block is stored as FEC block
boundary information in the header of each packet. When FEC is
optionally applied, FEC flag information is also stored in the
header. If the number of source packets or repair packets of the
FEC block is variable, information about the number of packets or
the number of source packets and information about the number of
source packets or the number of repair packets of the FEC block may
also be stored in the header.
[0162] In accordance with an exemplary embodiment of the present
invention, a sender may transmit content to which FEC is optionally
applied, by signaling or transmitting FEC configuration-related
information or other encoding configuration-related information to
a receiver. In addition, the sender may optionally apply FEC
depending on the network conditions or content QoS. Further, by
periodically repeatedly transmitting all or some of FEC control
information including FEC configuration-related information or
other encoding configuration-related information, or by
transmitting all or some of FEC configuration-related information
by the proposed in-band signaling method, the sender may provide
the FEC configuration-related information even to a new receiver in
the situation where the service is already in progress, so that the
new receiver may also recover the lost data by performing FEC
decoding, making it possible to provide high-quality services to
users.
[0163] If there is a plurality of data streams, i.e. source flows,
output from an application layer, then it is preferable that the
transmission system stores information for distinguishing the
multiple streams in an FEC packet, for example, FEC Flow ID
information, and also stores the same information even in an FEC
packet for a stream or a parity flow comprised of a parity payload,
which is generated for FEC protection of the stream, during their
transmission, thereby allowing the receiver to determine the stream
of parity payloads related to each of the multiple streams.
[0164] Alternatively, if there is a plurality of data streams
output from an application layer, then it is preferable that the
transmission system stores information for distinguishing each data
stream and each parity payload stream or a parity flow in an FEC
packet, for example, a source flow ID and a parity flow ID, during
its transmission, and then transmits mapping information to the
parity stream, for example, FEC Flow ID 1=Source Flow ID 1+Parity
Flow ID 1, generated for FEC protection of each data stream, as
separate control information which is different from the FEC
packet.
[0165] As a result, a receiving apparatus may distinguish each data
stream based on the stream identification information in the FEC
packet or the separate control information different from the FEC
packet, and may determine the parity stream generated for FEC
protection of each data stream, so that the receiving apparatus can
smoothly perform FEC decoding.
[0166] As is apparent from the foregoing description, according to
exemplary embodiments of the present invention, a receiving
apparatus may provide high-quality services to users, and may
easily distinguish an FEC packet by the FEC packet configuration
method of the exemplary embodiments described above.
[0167] While the invention has been shown and described with
reference to certain exemplary embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims and
their equivalents.
* * * * *